how to check if a specefic attribut does exist in odoo DB?

Question

as you can see here my class in python

class recrutement(osv.osv):

_name = "recrutement"
_decription = "recrutement"
_columns = {
    'name' :fields.char ( 'رقم المقرر ' ,size=64, required=False, select=True),
    'nom_cand' :fields.many2one ('hr.employee','اسم الموظف' ,size=64, required=False, select=True),
    'date_recrutement':fields.date("تاريخ التنصيب",required=True),
    'state': fields.selection([('draft', 'recrutement-Brouillon'),('confirm', 'CSPI'),
    ('state3', 'SG'), ('state4', 'Directeur'), ('state5', 'Secrétaire Général'), ('state6', 'Directeur')],
    'Etat', readonly=True, track_visibility='onchange', copy=False),}

output: my output

what I want to do is a function in python to stop the insertion if the second attribute does exist, in another way: ('name' Rec00.. )can have only one ('nom_cand' bouzoudja ) and 'nom_cand' can't have more than one name (Rec005, Rec006, ...)

Answer 1

You can use sql constraints for that.

_sql_constraints = [('unique_name_nom_cand', 'unique(name, nom_cand)', 'Combination already available')]